1. Field of the Invention
The present invention relates to an apparatus and a method for diagnosing deterioration of an oxygen sensor of a vehicle. More particularly, the present invention relates to an apparatus and a method that diagnoses deterioration of the oxygen sensor when a difference between an exhaust gas recirculation (EGR) amount detected by a mass air flow (MAF) sensor and an exhaust gas recirculation (EGR) amount detected by an oxygen sensor occurs.
2. Description of Related Art
Generally an oxygen sensor is mounted on a vehicle for adjusting an air-fuel ratio by determining a mixing ratio between air and a fuel in a combustion chamber of an engine.
The oxygen sensor performs air-fuel ratio control by detecting an oxygen content amount among exhaust gas and determining a fuel mixing ratio. Thus, fuel consumption is improved and exhaust gas is reduced.
Meanwhile, a mass air flow (MAF) sensor which detects an intake air amount drawn into the engine is mounted on the vehicle to operate the engine appropriately.
Generally, an exhaust gas recirculation (EGR) system is provided to a vehicle for reducing noxious exhaust gases of the vehicle. The amount of nitrogen oxide in the exhaust gas is increased in an oxygen rich air mixture, and the air mixture is combusted well. Therefore the exhaust gas, as a consequence of a part of the exhaust gas being recirculated to the air mixture in order to reduce the oxygen ratio in the air mixture, hinders combustion.
The MAF sensor and the oxygen sensor that are mounted on the vehicle as stated above control an exhaust gas recirculation (EGR) amount. That is, a controller controls the EGR amount by measuring the intake air by the MAF sensor before activating the oxygen sensor, and on the contrary, the controller controls the EGR amount by detecting the oxygen content of the exhaust gas by the oxygen sensor after activating the oxygen sensor.
If the oxygen sensor does not detect the oxygen amount among exhaust gas on account of deterioration or malfunction, the controller can't control a fuel amount supplied to the engine cylinder. Thus, the exhaust gas may include harmful components.
The information disclosed in this Background section is only for enhancement of understanding of understanding of the general background of the invention and should not be taken an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.